Passive Radar Direct Wave And The Interference Signal Suppression

The passive radar utilizes commercial FM broadcast station, TV station, or cellular phone base to detect and track targets by receiving and processing echoes from transmitters of opportunity. Such radar system has received much interest from many countries because of its particularities, such as anti-stealth ability, anti-jamming and anti-reconnaissance.This thesis focuses on some of the key techniques such as adaptive removal of the direct signal and multi-path, and the separation of the co-channel interference in the passive radar based on FM broadcast signals. The main work of the thesis can be summarized as follows:(1). The signal model of the passive radar based on FM broadcast is introduced for the following two cases: (i) the signal is interfered by a co-channel interference and (ii) the signal is free of the co-channel interference. The signal component, frequency properties, the ambiguity function of the FM broadcast signals is analyzed.(2). The adaptive filter algorithms, such as Least Mean Square algorithm (LMS), Normalized LMS algorithm, Recursive Least Square algorithm as well as Extensive Cancellation algorithm is discussed and applied in the suppression of the direct signal and multi-path. The suppression performance of the adaptive filter introduced above are analyzed and discussed.(3). According to the analysis of the component and the statistic characters of received signal in the main received channel, and the research of the blind sources separation technique based on the Independent Component Analysis (ICA), a novel signal processing scheme based on ICA for the separation of the co-channel signal is proposed. Theoretical analysis and simulation results demonstrate the feasibility and validity of the proposed scheme.